In the design of railroad system, it has become common practice to utilize electric locomotives and self-propelled cars which draw electric power from overhead wires via carbon collectors mounted on pantographs. The carbon collectors make sliding contact with the lower surface of the wire suspended thereover. See D. L. Dixon, "Development with Carbons for Current Collection", Railway Engineering Journal, Vol. 2, No. 5, pp. 46-59 (September 1973) for a history of the development of carbon collectors for use with pantographs. Carbon for pantograph applications may be made by any one of a number of processes (See Liggett, "Carbon-Baked and Graphitized, Products, Manufacture", Encyclopedia of Chemical Technology, Vol. 4, 2d.Ed., pp. 158-202 (1964). Carbon has become a preferred material for pantograph current collectors because it offers greatly decreased wear of the overhead wire and of the carbon in comparison with the metal collectors used previously. Moreover, lubrication is not necessary with carbon shoes. However, the grades of carbon used all suffer from the same defect, that of brittleness. As the overhead wire is usually suspended from a catenary cable by hangers, which tend to come loose and hang below the wire, the shoes often strike these hangers with extremely detrimental results. Moreover, the overhead wire is usually discontinuous, such discontinuities occurring at the junction of electrically isolated "sections" and at appurtenances such as draw bridges. Frequently foreign objects are maliciously or accidentally thrown over the overhead wire. Impact with any such objects causes chipping or fracture of the carbons. As most locomotives are fitted with a pluality of carbon collectors, this breakage does not often lead to an interruption of service; however, the carbons must be more frequently inspected and serviced than is desirable, and in fact many pantograph carbons are broken before they wear out, and must be discarded. The difficulty, of course, is further compounded by high train speeds, which are increasingly common.